In my opinion, to link 'two-dimensional iconography' with 'Zen' simplicity is by itself a misjudged notion. Microsoft and its designers are merely following a trend of minimalism which is as fashionable and ostentatious as Apple's skeuomorphism and 7's glass.

Simplicity can be achieved with conventional design elements. Traditional or common designs usually achieve a degree of simplicity just by virtue of their familiarity.

That's not to say design shouldn't evolve. But being able to distinguish between avante-garde and truly transformational would help in keeping an objective viewpoint.

What you call ostentatious, I call simple, quick and easy to use. When I first saw the advertisements for WP7 touting its quick and simple access to important information, I passed it off as the usual marketing fluff we've grown accustomed to from Microsoft. A year later, I finally tried a WP7 phone and was completely blown away by the interface. It was exactly what I had been looking for in a mobile OS.

I realize that it's not for everyone, and market share numbers certainly reflect that, but for once it seems like Microsoft really gets it when it comes to good UI design.

Simplicity can be achieved with conventional design elements.

I'm sorry, but it doesn't get much simpler than plain text and line-art icons on monochromatic background colors. How much simpler does it have to become to differentiate it from the rampant skeuomorphism of iOS and Android in your eyes? The only thing simpler than the current Metro design would be a complete CLI interface, which ironically would drastically complicate the use of a phone for anything other than controlling a webserver remotely.

I'll maintain that my preference for clean, simple, useful design meshes very well with my personal nature, despite your opinion on the meaning of Zen.